Printer controllers face difficulties when they have to send print data to two or more printhead modules in a printhead, each of the modules having one or more rows of print nozzles for outputting ink. In one embodiment favoured by the applicant, data for each row is shifted into a shift register associated with that row.
The applicant has discovered that some manufacturing advantages arise when printhead modules of different lengths are used within a product range. For example, a particular width of printhead for a pagewidth printer can be achieved with various different combinations of printhead module. So, a 10 inch printhead can be formed from two 5 inch printhead modules, a 6 and a 4 inch module, or a 7 and a 3 inch module.
Whilst useful in some ways, printhead modules of different lengths raise some other issues. One of these is that when one of the modules is longer, it must be loaded with more data than the other module in a given load period. One way of dealing with the problem is to use a printer controller with sufficient processing power and data delivery capabilities that the data imbalance is not problematic. Alternatively, in some cases it may be feasible to add one or more additional printer controllers to help deal with the high data rates involved. However, if the data rates for the printer controller providing data to the longer printhead module are already relatively close to that printer controller's capabilities, it may be not be commercially feasible for either of these solutions to be implemented.
It would be useful to provide a printhead module that addresses at least some of the disadvantages of known printhead modules.